The impact of smoking cessation on respiratory symptoms, lung function, airway hyperresponsiveness and inflammation

Abstract

Smoking is the main risk factor in the development of chronic obstructive pulmonary disease (COPD), and smoking cessation is the only effective treatment for avoiding or reducing the progression of this disease.Despite the fact that smoking cessation is a very important health issue, information about the underlying mechanisms of the effects of smoking cessation on the lungs is surprisingly scarce. It is likely that the reversibility of smoke-induced changes differs between smokers without chronic symptoms, smokers with nonobstructive chronic bronchitis and smokers with COPD. This review describes how these three groups differ regarding the effects of smoking cessation on respiratory symptoms, lung function (forced expiratory volume in one second), airway hyperresponsiveness, and pathological and inflammatory changes in the lung.Smoking cessation clearly improves respiratory symptoms and bronchial hyperresponsiveness, and prevents excessive decline in lung function in all three groups.Data from well-designed studies are lacking regarding the effects on inflammation and remodelling, and the few available studies show contradictory results. In chronic obstructive pulmonary disease, a few histopathological studies suggest that airway inflammation persists in exsmokers. Nevertheless, many studies have shown that smoking cessation improves the accelerated decline in forced expiratory volume in one second, which strongly indicates that important inflammatory and/or remodelling processes are positively affected.

Occupational exposure to dust, gases and fumes, a family history of asthma and impaired respiratory health

“…This finding indicates that also exposure for a long time before the survey may have had effects. This finding is also in accordance with our previous results, in which retired miners had an increased prevalence of respiratory symptoms (22) and respiratory symptoms were more common among ex-smokers than among nonsmokers (23).…”

Socio-economic status is related to incidence of asthma and respiratory symptoms in adults

“…This is in line with a report that reviewed the effect of smoking cessation. This found that the prevalence of respiratory symptoms remained higher in ex-smokers for many years compared with nonsmokers [29]. Passive smoking is associated with asthma and respiratory symptoms [17,30], and it is disappointing that data about passive smoking were not available.…”

Optimising pharmacological maintenance treatment for COPD in primary care

“…15,16,20 We hypothesise that the curve based on these new data presents a very different picture from the original curve on which our current understanding of COPD has been based ( Figure 1B). The effect of smoking cessation in mild to moderate COPD (GOLD stage I-II) is based on the results of several studies, 13 including the Lung Health study, 21 which showed that early smoking cessation is associated with reduced decline in lung function. Few studies have examined the effect of smoking cessation in late stage COPD.…”

“…Smoking cessation is the single most effective intervention for reducing the risk of developing COPD and slowing its progression. [11][12][13] Management of COPD requires adoption of healthy behaviours and long-term pharmacotherapy to maintain QoL and minimise disease burden. Recent evidence indicates that initiating maintenance therapy with long-acting bronchodilator treatment at the early stages of COPD, when symptoms are more than intermittent, may have a significant impact on reducing the impact of the disease.…”